From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14CBFC433E2 for ; Tue, 1 Sep 2020 16:25:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF8C62078B for ; Tue, 1 Sep 2020 16:25:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731036AbgIAQZT (ORCPT ); Tue, 1 Sep 2020 12:25:19 -0400 Received: from gofer.mess.org ([88.97.38.141]:36619 "EHLO gofer.mess.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730027AbgIAQZO (ORCPT ); Tue, 1 Sep 2020 12:25:14 -0400 Received: by gofer.mess.org (Postfix, from userid 1000) id 7D41DC63F2; Tue, 1 Sep 2020 17:25:12 +0100 (BST) Date: Tue, 1 Sep 2020 17:25:12 +0100 From: Sean Young To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Jia-Ju Bai , Mauro Carvalho Chehab , Sasha Levin Subject: Re: [PATCH 4.19 016/125] media: pci: ttpci: av7110: fix possible buffer overflow caused by bad DMA value in debiirq() Message-ID: <20200901162512.GA30837@gofer.mess.org> References: <20200901150934.576210879@linuxfoundation.org> <20200901150935.368387062@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200901150935.368387062@linuxfoundation.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Greg, On Tue, Sep 01, 2020 at 05:09:31PM +0200, Greg Kroah-Hartman wrote: > From: Jia-Ju Bai > > [ Upstream commit 6499a0db9b0f1e903d52f8244eacc1d4be00eea2 ] > > The value av7110->debi_virt is stored in DMA memory, and it is assigned > to data, and thus data[0] can be modified at any time by malicious > hardware. In this case, "if (data[0] < 2)" can be passed, but then > data[0] can be changed into a large number, which may cause buffer > overflow when the code "av7110->ci_slot[data[0]]" is used. > > To fix this possible bug, data[0] is assigned to a local variable, which > replaces the use of data[0]. See the discussion here: https://lkml.org/lkml/2020/8/31/479 It does not seem worthwhile merging to the stable trees. Thanks Sean > > Signed-off-by: Jia-Ju Bai > Signed-off-by: Sean Young > Signed-off-by: Mauro Carvalho Chehab > Signed-off-by: Sasha Levin > --- > drivers/media/pci/ttpci/av7110.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/media/pci/ttpci/av7110.c b/drivers/media/pci/ttpci/av7110.c > index d6816effb8786..d02b5fd940c12 100644 > --- a/drivers/media/pci/ttpci/av7110.c > +++ b/drivers/media/pci/ttpci/av7110.c > @@ -424,14 +424,15 @@ static void debiirq(unsigned long cookie) > case DATA_CI_GET: > { > u8 *data = av7110->debi_virt; > + u8 data_0 = data[0]; > > - if ((data[0] < 2) && data[2] == 0xff) { > + if (data_0 < 2 && data[2] == 0xff) { > int flags = 0; > if (data[5] > 0) > flags |= CA_CI_MODULE_PRESENT; > if (data[5] > 5) > flags |= CA_CI_MODULE_READY; > - av7110->ci_slot[data[0]].flags = flags; > + av7110->ci_slot[data_0].flags = flags; > } else > ci_get_data(&av7110->ci_rbuffer, > av7110->debi_virt, > -- > 2.25.1 > >